Conceptually the task of a direct digital modulation scheme can be accomplished based on the proper selection of edges from a uniform grid of edge positions aligned to a base oscillator frequency and temporal distance between the edge positions based on phase-modulation information. Phase-modulation in general creates phase-jumps in the carrier-signal and can significantly reduce distance between signal edges to be generated from the distance between edges of the base oscillator signal. These reduced distances between edges can require an increase in speed of about a factor of two in the phase modulation circuitry that can include multiplexers and address-computation modules in the selection logic.